Originally Posted by SubaruDude2.5RS

Nothing internally. Maybe a bigger Turbo, Injectors, and a FMIC. Internally the JDM heads are some of the best ever made, maybe get new cams, but the only cams that make a change in power cost around $1,500 ( tooooo much $ for 20 hp.) Everything else is forged internally. The motor can handle 30 Psi with 110 octaine race fuel without mods to the block. The rev. limit is 8200 RPM's I might buy a Ralli Tek bullet rear Diff. Again, alot of $green$ . You might laugh but my engine has its own version of V-tec on it. Subaru calles it AVCS (Active Valve Control System). I am going to put a full Tein set-up for my handling mods (I'm mostly going to auto-x the car)